Hydrocarbon conversion processes often employ a series of reaction zones through which hydrocarbons pass. Each reaction zone may have its own unique process requirements, including a required temperature. Accordingly, each reaction zone requires a sufficient amount of heating upstream of the reaction zone to achieve the required temperature for performing the desired hydrocarbon conversion therein.
One well-known hydrocarbon conversion process is catalytic reforming. Catalytic reforming is a well-established hydrocarbon conversion process employed in the petroleum refining industry for improving the octane quality of hydrocarbon feed streams. The primary product of catalytic reforming is a gasoline blending component or a source of aromatics for petrochemicals. Reforming may be defined as the total effect produced by dehydrogenation of cyclohexanes and dehydroisomerization of alkylcyclopentanes and high carbon content C6 to C7 naphthenes to yield aromatics, dehydrogenation of paraffins to yield olefins, dehydrocyclization of paraffins and olefins to yield aromatics, isomerization of n-paraffins, isomerization of alkylcycloparaffins to yield cyclohexanes, isomerization of substituted aromatics, and hydrocracking of paraffins. A reforming feed stream can be a product stream from a hydrocracker, straight run, FCC, or coker, and can contain many other components such as a condensate or a thermal cracked naphtha.
Heaters or furnaces are often used in hydrocarbon conversion processes, such as reforming, to heat the process fluid before it is reacted. Generally, fired heaters or furnaces include a radiant fired heating zone to heat the fluid, with a convective section being used for another service, such as producing steam. Each section includes tubes to contain the process fluid flowing through the heater.
In view of the rising costs of fuel, conventional designs suffer disadvantages. Specifically, the production of steam by convective sections is non-optimal as steam is provided in other areas of hydrocarbon processing plants. Rather, heat from the fuel combusted in the radiant fired heating zone can be better concentrated on an increase in enthalpy in hydrocarbon processing.
Accordingly, it is desirable to provide methods and apparatuses for processing hydrocarbons utilizing convective sections to heat hydrocarbon streams. Further, it is desirable to control flow of hydrocarbon streams to convective sections and radiant fired heating zones. Also, it is desirable to provide such methods and apparatuses that operate economically. Furthermore, other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawing and the foregoing technical field and background.